Hair partially disappearing in render after combing
You have $300000$ individual hairs right now. I suspect that your issue stems from that very high number of edited particles. To fix this, use Particle Children. Set your Emission number to something lower, like $3000$ or $1000$. Then, enable Interpolated children:



You can set the Render parameter so that the total number of children is equal to $300000$, (i.e. $3000\cdot 100=300000$).

You can now use Particle Edit to comb your particles. They should take up less memory now, and hopefully render correctly.